I recently had an excellent day trip on the Edisto River near Cottageville, SC (about 30-40 miles from Charleston). Started at Givhan's Ferry State Park and went to Long Creek public landing. The trip took about 4.5 hours with a break for lunch of about 30 minutes. The river is excellent in this portion, with a wide variety of scenery. Width ranges from over 100 feet to some very narrow parts. However, we nearly passed the Long Creek landing. Luckily a local boater informed us that this landing is actually back in a cove and not visible from the main river. When looking for this landing, use the large sand bar as a landmark for the point where you turn back into a cove and paddle upstream for about 5 minutes.
From Charleston, head straight out on HW 61 past Summerville. Givhans Ferry state park is just off 61 and very well marked.
Coastal Expeditions Map was very helpful and can be purchased online or over the phone.